This application is related to and claims priority from Japanese Patent Application No. Hei. 11-220830 filed on Aug. 4, 1999, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a filter device with a magnetic member, which can filter impurities mixed in a fluid and can remove a very fine iron powder contained in the fluid.
2. Description of Related Art
In a conventional oil filter having a magnetic member described in JP-A-11-156120, a protection member having plural holes is provided inside an element assembly having a filter element, and the magnetic member is held by an engagement claw of a holder provided at an inner peripheral side of the protection member. However, it is necessary to assemble the magnetic member into the holder, and assembling steps of the filter device becomes trouble. Further, in a case where the oil filter is used for an internal combustion engine, when the magnetic member or the engagement claw of the holder falls away from the protection member due to vibrations in the internal combustion engine, an oil passage within the oil filter may be closed, or an oil passage within the internal combustion engine may be closed after the fallen part moves into the internal combustion engine.
In view of the foregoing problems, it is an object of the present invention to provide a filter device provided with a magnetic member, in which a holding state of the magnetic member can be sufficiently maintained with a simple structure.
According to the present invention, in a filter device with a magnetic member, an approximate cylindrical protection member is disposed to be inserted into an inner space defined by an approximate cylindrical inner peripheral surface of an element assembly having a filter element for filtering a fluid, a recess portion recessed from an outer peripheral surface of the protection member toward an inner radial side is provided in the protection member, and the magnetic member is disposed to be joined to the recess portion and to be close to the inner peripheral surface of the element assembly. Thus, a holding state of the magnet member can be sufficiently maintained without depending on a contact state between the magnetic member and the recess portion. Accordingly, the filter device with the magnetic member can filter impurities mixed in oil and can remove very fine iron powder contained in oil, while the holding state of the magnetic member can be sufficiently maintained with a simple structure.
Preferably, the protection member is made of a ferromagnetic material. Therefore, when the magnetic member contacts the protection member, the protection member is magnetized, and removing performance of the very fine iron powder contained in the-fluid can be further improved.
More preferably, the magnetic member has a dimension in a radial direction of the protection member, approximately equal to a recessed dimension of the recess portion in the radial direction. Therefore, the magnetic member can be accurately sufficiently held between the recess portion of the protection member and the element assembly with a simple structure.